• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 483
  • 107
  • 98
  • 66
  • 50
  • 19
  • 18
  • 10
  • 8
  • 7
  • 6
  • 5
  • 5
  • 5
  • 4
  • Tagged with
  • 1135
  • 115
  • 86
  • 81
  • 70
  • 65
  • 64
  • 58
  • 54
  • 54
  • 52
  • 52
  • 45
  • 45
  • 45
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
231

Chemical Analysis of Mountain Sheep Forage in the Virgin Mountains, Arizona

Morgart, John R., Krausman, Paul R., Brown, William H., Whiting, Frank M. 07 1900 (has links)
No description available.
232

Mountain centered icefields in northern Scandinavia

Fredin, Ola January 2004 (has links)
<p>Mountain centered glaciers have played a major role throughout the last three million years in the Scandinavian mountains. The climatic extremes, like the present warm interglacial or cold glacial maxima, are very short-lived compared to the periods of intermediate climate conditions, characterized by the persistence of mountain based glaciers and ice fields of regional size. These have persisted in the Scandinavian mountains for about 65% of the Quaternary. Mountain based glaciers thus had a profound impact on large-scale geomorphology, which is manifested in large-scale glacial landforms such as fjords, glacial lakes and U-shaped valleys in and close to the mountain range.</p><p>Through a mapping of glacial landforms in the northern Scandinavian mountain range, in particular a striking set of lateral moraines, this thesis offers new insights into Weichselian stages predating the last glacial maximum. The aerial photograph mapping and field evidence yield evidence that these lateral moraines were overridden by glacier ice subsequent to their formation. The lateral moraines were dated using terrestrial cosmogenic nuclide techniques. Although the terrestrial cosmogenic nuclide signature of the moraines is inconclusive, an early Weichselian age is tentatively suggested through correlations with other landforms and stratigraphical archives in the region. The abundance and coherent spatial pattern of the lateral moraines also allow a spatial reconstruction of this ice field. The ice field was controlled by topography and had nunataks protruding also where it was thickest close to the elevation axis of the Scandinavian mountain range. Outlet glaciers discharged into the Norwegian fjords and major valleys in Sweden.</p><p>The process by which mountain based glaciers grow into an ice sheet is a matter of debate. In this thesis, a feedback mechanism between debris on the ice surface and ice sheet growth is presented. In essence, the growth of glaciers and ice sheets may be accelerated by an abundance of debris in their ablation areas. This may occur when the debris cover on the glacier surface inhibits ablation, effectively increasing the glaciers mass balance. It is thus possible that a dirty ablation area may cause the glacier to advance further than a clean glacier under similar conditions. An ice free period of significant length allows soil production through weathering, frost shattering, and slope processes. As glaciers advance through this assemblage of sediments, significant amounts of debris end up on the surface due to both mass wastage and subglacial entrainment. Evidence that this chain of events may occur, is given by large expanses of hummocky moraine (local name Veiki moraine) in the northern Swedish lowlands. Because the Veiki moraine has been correlated with the first Weichselian advance following the Eemian, it implies a heavily debris charged ice sheet emanating from the mountain range and terminating in a stagnant fashion in the lowlands.</p>
233

Estimating Wind Velocities in Atmospheric Mountain Waves Using Sailplane Flight Data

Zhang, Ni January 2012 (has links)
Atmospheric mountain waves form in the lee of mountainous terrain under appropriate conditions of the vertical structure of wind speed and atmospheric stability. Trapped lee waves can extend hundreds of kilometers downwind from the mountain range, and they can extend tens of kilometers vertically into the stratosphere. Mountain waves are of importance in meteorology as they affect the general circulation of the atmosphere, can influence the vertical structure of wind speed and temperature fields, produce turbulence and downdrafts that can be an aviation hazard, and affect the vertical transport of aerosols and trace gasses, and ozone concentration. Sailplane pilots make extensive use of mountain lee waves as a source of energy with which to climb. There are many sailplane wave flights conducted every year throughout the world and they frequently cover large distances and reach high altitudes. Modern sailplanes frequently carry flight recorders that record their position at regular intervals during the flight. There is therefore potential to use this recorded data to determine the 3D wind velocity at positions on the sailplane flight path. This would provide an additional source of information on mountain waves to supplement other measurement techniques that might be useful for studies on mountain waves. The recorded data are limited however, and determination of wind velocities is not straightforward. This thesis is concerned with the development and application of techniques to determine the vector wind field in atmospheric mountain waves using the limited flight data collected during sailplane flights. A detailed study is made of the characteristics, uniqueness, and sensitivity to errors in the data, of the problem of estimating the wind velocities from limited flight data consisting of ground velocities, possibly supplemented by air speed or heading data. A heuristic algorithm is developed for estimating 3D wind velocities in mountain waves from ground velocity and air speed data, and the algorithm is applied to flight data collected during “Perlan Project” flights. The problem is then posed as a statistical estimation problem and maximum likelihood and maximum a posteriori estimators are developed for a variety of different kinds of flight data. These estimators are tested on simulated flight data and data from Perlan Project flights.
234

Structural development of the Dun Mountain Ophiolite Belt in the Permian, Bryneira range, Western Otago, New Zealand.

Adamson, Thomas Keeley January 2008 (has links)
The deformed Permian Dun Mountain Ophiolite Belt (DMOB) forms the basement of the Dun Mountain-Maitai terrane and is traceable through the entire length of New Zealand. The DMOB contains a variably serpentinised mantle portion and a crustal portion containing gabbros, dolerites, cross cutting dikes and extrusives, together they are similar to oceanic crust. The initial crustal portion, however, is atypical when compared to other ophiolites, being thin and lacking a sheeted dike complex, but has well spaced inclined intrusive sheets and sills. At least four post-Permian deformation periods affect the DMOB; collision and rotation during emplacement of the DMOB on the Gondwana margin, compression during Mesozoic orogenies, extensional deformation during the Gondwana break-up and transpressive deformation related to the modern plate boundary through New Zealand. Structural work in the Northern Bryneira Range focused on well preserved outcrops to investigate crustal growth and contemporaneous deformation during the Permian. Structural evidence of Permian deformation was determined by examination of pseudostratigraphy, structures constrainable to the Permian, and the geometric relationships with the overlying Maitai sedimentary sequence. Crosscutting by intrusive phases was used to determine a chronological order of crustal growth and deformation episodes. It was concluded that all deformation was extensional and that two major phases of magmatism were separated by a period of deformation and were followed by ongoing syn-sedimentary deformation during the deposition of the Maitai Group. After removal of Mesozoic rotation, the resulting orientations of paleo-horizontal markers and diverse orientations of intrusive sheets were analysed. Two hypothesises were tested to assess the origin of inclined intrusive sheets: a) that the diverse orientations were the result of tectonic rotation coeval with the intrusion of dikes. b) that primary orientations of the sheets had been diverse. Results show that the sheets were intruded with diverse orientations, probably related to variation in the principle horizontal stress over time. Further rotation of the assemblage of sheets occurred during the last stages of magmatism and during the subsequent period of sedimentation. The last stage probably relates to large scale normal faulting during the development of the sedimentary basin. iii
235

Mountain sheep habitat characteristics in the Pusch Ridge Wilderness, Arizona

Etchberger, Richard Carl, 1957- January 1988 (has links)
Mountain sheep (Ovis canadensis mexicana) in the Pusch Ridge Wilderness (PRW), Santa Catalina Mountains, Arizona have abandoned historic habitat and now occupy 44 km². I used univariate analyses to quantify differences of physiographic and vegetational variables between abandoned habitat and habitat that is still used by mountain sheep. A discriminant function model characterized the magnitude of the differences between the 2 habitats. Habitat that supports mountain sheep has less human disturbance and is more open with more side oats grama (Bouteloua curtipendula), red brome (Bromus rubens), brittle bush (Encelia farinosa), and forb cover, but less ground cover, bush muhly (Muhlenbergia porteri), and turpentine bush (Haplopappus laricifolius) than habitat that was abandoned by mountain sheep. Fire is important in still used habitat because it reduces tall plants that obstruct mountain sheep vision. Human disturbances should be minimized in mountain sheep habitat.
236

Young children’s understanding of line of sight

Boydell, Mark M. January 2005 (has links)
Previous research into children’s understanding of line of sight has led to differing conclusions as to when and how children become able to appreciate that their view of an object will be different from another persons’ view of the same object. This is probably due to the diversity of response methods required from the children as well as different types of tasks and settings being used between the experiments. The aim of the present thesis is to investigate systematically how children will fare across various settings and whether their comprehension of line of sight can be biased by the task’s setting. The first experiment assessed children’s understanding of line of sight through a tube that was bent to varying degrees of curvature and whether their response pattern would change when feedback was provided. Results showed that children have great difficulty performing correctly on this task, especially when the degree of curvature is small. The older children corrected their response pattern when feedback was provided but the younger children tended to persevere in their response pattern regardless of contradictory feedback. The second experiment looked at children’s performance when walls were used - half the walls were smooth gradual curves while the other half was walls made up of two segments that met to form an angle. Again the children were asked to predict if two dolls placed at opposite ends of each wall would be able to see each other. Results showed that though even young children have no trouble in performing correctly on the “angled” walls, performance on the curved walls was significantly poorer with the older children performing better than the younger children. The third experiment sought to quantify the point at which children deemed line of sight became possible. To do this we used a single “U” shaped trench with the children being asked if one doll could see another in various configurations. The results showed a strong bias towards over estimating visibility. The fourth experiment repeated the second experiment but used wooden trenches instead of walls but also sought to quantify the “switchover” point at which the children deem vision becomes possible between the two dolls. The difference between angles and curves was once again replicated as was the age difference. The fifth experiment compared children’s appreciation of line of sight through/along tubes, trenches and walls. This performance level varied strongly depending on the type of task the child was asked to perform upon with the tube proving to be the most difficult and the angled trench the easiest. The overall findings of the experiment pointed to a context-dependent performance, implying a piece-meal development of childrens’ comprehension of line of sight.
237

Baking Dalarna's biking cake : Collaboration as a means for destination competitiveness, a case study of “Biking Dalarna"

Yachin, Jonathan Moshe January 2013 (has links)
In the contemporary tourism industry, the competitive game is between destinations. Tourism operations struggle to remain competitive on the international market and their success depends to a large extent on other complementary and competing tourism organizations at the destination. It is the sum of the total tourism offerings at the destination which determines its attractiveness. This research explores tourism collaboration process as a means of generating destination competitiveness. The focus of the research is on the enhancing factors which contribute to the success of the collaboration and to the development of quality tourism products. The research studies the case of Biking Dalarna, a collaboration of different organizations at five biking destinations in Dalarna, Sweden. Its purpose is to develop biking tourism in the region and to make Dalarna into Sweden’s leading biking destination. It is a qualitative research; the empirical data was collected through in depth interviews with representatives of six Biking Dalarna member organizations. The qualitative data collected from the participants provides inside look into the members reflections and experience of collaborating. The findings of this research demonstrate how collaboration has improved the biking product in Dalarna and promoted solutions to development problems. The research finds the good relationship between the collaborating actors and the involvement and leadership of the regional tourism management organization as the most contributing factors to the success of Biking Dalarna. The research also suggests that a third desired outcome of collaboration, improved marketing attributes was yet to be achieved in the case of Biking Dalarna.
238

The mountain pine beetle, climate change, and scientists : understanding science's responses to rapid ecological change in Western Canada

Lettrari, Heike 01 June 2017 (has links)
Today, climate change and rapid ecological change are impacting our ecosystems and landscapes in numerous, often surprising ways. These changes result in social, cultural, ecological, and economic shifts, as exemplified in the climate-exacerbated mountain pine beetle (MPB) outbreak in British Columbia. Recently, scientific communities have boosted calls for “usable science.” By interviewing leading MPB scientists, I ask, “How are scientists and their institutions responding to rapid ecological change?” Numerous factors shape MPB science—institutional support, funding, and values—and these factors enable and constrain effective relationships and ultimately, useful science, in response to the outbreak. Results suggest that while science and scientific institutions change slowly, and while relationships between MPB science and policy are characterized as tenuous, there are signs that crossing institutional boundaries (such as the TRIA Network) contributes to producing science that is more effective for responding to rapid ecological change. / Graduate
239

Decision criteria for the use of cannon-fired precision munitions

La Rock, Harold L. 06 1900 (has links)
The U.S. Army and Marine Corps are developing guided munitions for cannon artillery. These munitions provide a significant increase in range and accuracy, but the tactics, techniques, and procedures used to employ them have yet to be developed. This study is intended to assist with that development by providing a method to determine when to use these munitions rather than conventional munitions in order to achieve a tactical-level commander's desired objectives. A combination of multi-attribute utility theory and simulation are used to determine the best ammunition (precision or conventional) to fire under certain battlefield conditions. The simulation, developed by the U.S. Army Research Laboratory, provides results on the full range of artillery effects by varying the different battlefield conditions that have the greatest effect on the accuracy of artillery. The results of simulated artillery fire missions are studied to determine the combination of battlefield conditions that produce the best results for each type of ammunition. A decision model is used to account for a commander's expected preferences based on tactical considerations. The results vary greatly depending on the battlefield conditions and the commander's preferences. One type of projectile does not clearly dominate the other.
240

Census Tract 26.02: Mountain View

Arroyo, Jessica, Cain, Lilly, Luciano, Allison, Valencia, Briana, Wilson, Amberlee, Wilson, Andrew January 2017 (has links)
Poster / Soc 397a / 2017 Poverty in Tucson Field Workshop

Page generated in 0.0282 seconds